am-404 and palmidrol

Recent advances have dramatically increased our understanding of cannabinoid pharmacology: the psychoactive constituents of Cannabis sativa have been isolated, synthetic cannabinoids described and an endocannabinoid system identified, together with its component receptors, ligands and their biochemistry. Strong laboratory evidence now underwrites anecdotal claims of cannabinoid analgesia in inflammatory and neuropathic pain. Sites of analgesic action have been identified in brain, spinal cord and the periphery, with the latter two presenting attractive targets for divorcing the analgesic and psychotrophic effects of cannabinoids. Clinical trials are now required, but are hindered by a paucity of cannabinoids of suitable bioavailability and therapeutic ratio.

Topics: Amides; Amidohydrolases; Analgesics; Animals; Arachidonic Acids; Benzoxazines; Brain; Camphanes; Cannabinoid Receptor Modulators; Cannabinoids; Cell Membrane; Clinical Trials as Topic; Disease Models, Animal; Drug Design; Drug Interactions; Endocannabinoids; Enzyme Inhibitors; Ethanolamines; Glycerides; Humans; Injections, Spinal; Molecular Structure; Morpholines; Naphthalenes; Pain; Palmitates; Palmitic Acids; Piperidines; Plant Extracts; Polyunsaturated Alkamides; Pyrazoles; Receptors, Cannabinoid; Receptors, Drug; Rimonabant; Spinal Cord

The endocannabinoid N-arachidonylethanolamine (AEA) is accumulated by many cell types, but the mechanisms are unknown. Data from several laboratories are consistent with the hypothesis that the accumulation of AEA occurs via the action of a transmembrane carrier that binds and transports AEA. However, other data suggest that AEA is sufficiently lipophilic to transverse plasma membranes by passive diffusion and will accumulate if it is catabolized intracellularly. The controversy is muddied by the use of different cellular models and assays, all of which are assumed to be studying the same phenomena. The purpose of the studies reported herein was: first, to compare AEA accumulation and accumulation inhibitors in cerebellar granule neurons with a glioma cell line; and, second, to compare the neuronal accumulation of AEA with a closely related analog, N-palmitoylethanolamine (PEA). We have found that the accumulation of AEA by neurons and C6 glioma exhibits different affinity for AEA and inhibitor profiles. In addition, we find that the accumulation of AEA and PEA by neurons differs in the amount accumulated and in heterologous inhibition. These studies add to the evidence that the neuronal accumulation of AEA uniquely requires more than passive diffusion and fatty acid amide-mediated catabolism of intracellular AEA.

Topics: Amides; Animals; Animals, Newborn; Arachidonic Acids; Binding, Competitive; Biological Transport; Cell Line, Tumor; Cells, Cultured; Cerebellum; Endocannabinoids; Ethanolamines; Neurons; Palmitic Acids; Polyunsaturated Alkamides; Rats

Spasticity is a complicating sign in multiple sclerosis that also develops in a model of chronic relapsing experimental autoimmune encephalomyelitis (CREAE) in mice. In areas associated with nerve damage, increased levels of the endocannabinoids, anandamide (arachidonoylethanolamide, AEA) and 2-arachidonoyl glycerol (2-AG), and of the AEA congener, palmitoylethanolamide (PEA), were detected here, whereas comparable levels of these compounds were found in normal and non-spastic CREAE mice. While exogenously administered endocannabinoids and PEA ameliorate spasticity, selective inhibitors of endocannabinoid re-uptake and hydrolysis-probably through the enhancement of endogenous levels of AEA, and, possibly, 2-arachidonoyl glycerol-significantly ameliorated spasticity to an extent comparable with that observed previously with potent cannabinoid receptor agonists. These studies provide definitive evidence for the tonic control of spasticity by the endocannabinoid system and open new horizons to therapy of multiple sclerosis, and other neuromuscular diseases, based on agents modulating endocannabinoid levels and action, which exhibit little psychotropic activity.

Topics: Amides; Animals; Arachidonic Acids; Brain; Cannabinoid Receptor Modulators; Cannabinoids; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Endocannabinoids; Ethanolamines; Glycerides; Humans; Mice; Mice, Inbred Strains; Multiple Sclerosis; Palmitic Acids; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Receptors, Cannabinoid; Receptors, Drug; Rimonabant; Spasm; Spinal Cord

The biological actions of the endogenous cannabinoid anandamide are terminated by carrier-mediated transport into neurons and astrocytes, followed by enzymatic hydrolysis. Anandamide transport is inhibited by the compound N-(4-hydroxyphenyl)arachidonylamide (AM404). AM404 potentiates several responses elicited by administration of exogenous anandamide, suggesting that it may also protect endogenous anandamide from inactivation. To test this hypothesis, we studied the effects of AM404 on the plasma levels of anandamide using high-performance liquid chromatography/mass spectrometry (HPLC/MS). Systemic administration of AM404 (10 mg kg(-1) intraperitoneal, i.p. ) caused a gradual increase of anandamide in rat plasma, which was significantly different from untreated controls at 60 and 120 min after drug injection. In plasma, both AM404 and anandamide were associated with a plasma protein, which we identified as albumin by non-denaturing polyacrylamide gel electrophoresis. AM404 (10 mg kg(-1), i.p.) caused a time-dependent decrease of motor activity, which was reversed by the cannabinoid CB(1) receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide.hydrochloride (SR141716A, 0.5 mg kg(-1), i.p). These results are consistent with the hypothesis that AM404 inhibits anandamide inactivation in vivo.

Topics: Amides; Animals; Arachidonic Acids; Endocannabinoids; Ethanolamines; Male; Motor Activity; Palmitic Acids; Polyunsaturated Alkamides; Rats; Rats, Sprague-Dawley